why is my for loop using modulo giving me a weird output

perlynewby has asked for the wisdom of the Perl Monks concerning the following question:

I am using a for loop to get all the numbers divisible by 5 over 0 to 20(just a random num for now) but I don't understand the behavior now...please explain what i am not seeing

ultimately, I want to find all the number divisible by even numbers over a range of 0 to 10

use strict;
use warnings;
use integer;
use constant number => 5;
my %result;
for ( my $i=0; $i<=20 ;$i++){
    print $i%5,"\n";
    #here to test for % at even numbers
    }
[download]

output

0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 0 1 2 3 4 0

Comment on why is my for loop using modulo giving me a weird output Download Code

Replies are listed 'Best First'.
Re: why is my for loop using modulo giving me a weird output by Corion (Patriarch) on Jun 28, 2015 at 06:55 UTC
What other output did you expect? Maybe it helps you to tell us (in English) what the modulo operator returns and how that relates to a number being evenly divisible.	[reply]
Re^2: why is my for loop using modulo giving me a weird output by perlynewby (Scribe) on Jun 28, 2015 at 07:06 UTC
first, I tried with five just to check out how modulo worked nothing to do with even number yet. this is a incremental test code for me to learn perl code I expected the output to look like this: 1 2 3 4 this is because as I go thru the for loop, I goes thru 1,2,3,4,5,6,7,8,9,10,...,15,...20 but the for loop returns "0" 1 2 3 4( not as expected with "0") then it gives me the same output another 4 times. I don't understand the output being given 4 times. sorry for not being clearer perhaps this helps explain my question on iteration	[reply]
Re^3: why is my for loop using modulo giving me a weird output by afoken (Chancellor) on Jun 28, 2015 at 07:24 UTC
I tried with five just to check out how modulo worked https://en.wikipedia.org/wiki/Modulo_operation I expected the output to look like this: 1 2 3 4 Why? Modulo is the remainder of the division. 0 divided by 5 is 0, remaining 0. 1 divided by 5 is 0, remaining 1. 2 divided by 5 is 0, remaining 2. 3 divided by 5 is 0, remaining 3. 4 divided by 5 is 0, remaining 4. 5 divided by 5 is 1, remaining 0. 6 divided by 5 is 1, remaining 1. And so on. Alexander -- Today I will gladly share my knowledge and experience, for there are no sweeter words than "I told you so". ;-)	[reply]
Re^4: why is my for loop using modulo giving me a weird output by perlynewby (Scribe) on Jun 28, 2015 at 08:10 UTC
Re^5: why is my for loop using modulo giving me a weird output by marinersk (Priest) on Jun 28, 2015 at 08:50 UTC
Some notes below your chosen depth have not been shown here
Re^3: why is my for loop using modulo giving me a weird output by 2teez (Vicar) on Jun 28, 2015 at 07:16 UTC
Please read Corion again! Is there difference between printing, what modulo operator returns and using it to test? i.e `print 4%2; # or if (4%2 == 0) { # blah..blah... }` [download] Is there a difference? If you tell me, I'll forget. If you show me, I'll remember. if you involve me, I'll understand. --- Author unknown to me	[reply] [d/l]
Re^4: why is my for loop using modulo giving me a weird output by perlynewby (Scribe) on Jun 28, 2015 at 08:22 UTC
Re: why is my for loop using modulo giving me a weird output by GrandFather (Saint) on Jun 28, 2015 at 12:03 UTC
In Perl your for loop is better written: `for my $count (0 .. 20) { ... }` [download] Perl is the programming world's equivalent of English	[reply] [d/l]